public void findEvents(View view) {
    EditText usernameField = (EditText) findViewById(R.id.username);
    String username = usernameField.getText().toString().trim();
    currentTaskFind = new FindEventsTask();

    if (username.equals("")) {
      currentTaskFind.execute();
    } else {
      currentTaskFind.execute(username);
    }
  }
  @Override
  protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putSerializable(EventsKey, new ArrayList<Event>(events));
    outState.putSerializable(PreferenceKey, preference);

    // cancel active tasks
    if (currentTaskEvents != null) {
      currentTaskEvents.cancel(false);
    }
    if (currentTaskFind != null) {
      currentTaskFind.cancel(true);
    }
  }